$OpenBSD: patch-configure,v 1.11 2018/02/11 10:37:51 dcoppa Exp $

Index: configure
--- configure.orig
+++ configure
@@ -19500,7 +19500,7 @@ CPPFLAGS=$boost_thread_save_CPPFLAGS
 
 
 
-LDFLAGS+="$LDFLAGS $BOOST_THREAD_LDFLAGS"
+LDFLAGS="$LDFLAGS $BOOST_THREAD_LDFLAGS"
 LIBS="$LIBS $BOOST_THREAD_LIBS"
 
 # icu
